YABAQ (Yet another Bean Animal Question)

[biggertef]

I'm getting ready to pull the trigger on new tank and am struggling with nailing down the details of my overflow. The tank is going to be 48"x30"x22", roughly 135 gallons. I have read many posts on overflows, but I'm not yet quite sure on how to design the overflow. how many holes, what size, how big of a box. I am wanting to do a bean animal due to its 'fail safe' design. I am also pretty sure that I will be doing an internal trapezoidal flow in the back center of the tank

I calculated on Bean's site that a 1" drain can handle a fairly decent amount of water under full drain (~2000 gph with a 36" head height - 36" is just a ballpark guess at this point). For an even greater margin, I could go with 1.5" drains, which I am assuming would be plenty.

Here's where I get even more confused. 1.5" bulkheads are approximately 3.5" across so 3 of these would take up 10.5" if placed directly next to each other.. But.. I know we don't want to do that. So... here are my questions.. (I know.. you're thinking finally!!!)

How much spacing do I need in between each bulkhead?
What other spacing constraints do I need to account for? Standpipe fittings, distance from rear of tank, etc.
How many returns do I need and of what size? i am planning for 1300ish gph and pumps I have looked at have a 3/4" output. Do I just need one 3/4" fitting and split that in the overflow box to 2 loc lines?

My ultimate goal here is to determine hole sizes and overflow box size so that I can tell the LFS to order this puppy. Any guidance, links, winning lottery numbers, etc are appreciated.

 

[biggertef]

Still looking for those lottery numbers.. oh, and feedback on my overflow too

Still looking for those lottery numbers.. oh, and feedback on my overflow too

Continuing to research this and there seems to be a rule of thumb that holes should be spaced about 1 hole diameter apart. So, 3 - 3.5" holes would require 17.5" of linear real estate (10.5" for the holes themselves and 7" for spacing between the 3 holes) and this is without even considering the return. At these dimensions, my center overflow box is starting to swallow up the back wall! I forgot to mention in my first post that I am planning on vertical standpipes exiting through bulkeads in tank bottom.

Based on this, I believe that I will be going with the 1" drains, which according to Bean's calculator is still plenty for my setup. Hole sizes for these drains would be 1.88" each, which would require 9.5" for the 3 holes.

In addition to this, I am thinking a single 1.5" hole for a return, which I will split inside the overflow box to go to 2 loclines for return to the tank. Planning for a return pump that can deliver ~1200gph, after head calculated.

So, total real estate required would be 9.5" + 3" or 12.5".

Does this make sense? Any issues seen with this approach? Input appreciated.

 

[biggertef]

So.. I did some crude testing...

So.. I did some crude testing...

Being the paranoid type, I really, really wanted to have an understanding of the flow rates I could get with a full on siphon at 1". Well, I used a 5 gallon bucket redneck setup and did some ballpark testing. Obviously not gonna be exact, but it gives me a good feel for what a siphon can do.

Basically, I used a couple of threaded PVC adapters, one male, one female to make the 'bulkhead'. I drilled two holes in the bottom of a 5 gallon bucket for the bulkheads.

Connected to the bottom of the bulkheads were straight 1" PVC pipes going into an unused 40B (yeah, I know, sad).
Inside the bucket, I put 2 pieces of pipe. One tight fitting and one loose fitting.
I then filled the bucket to the brim and as simultaneously as I could, I started my stopwatch, aka smartyphone, and the siphon.

I ran this experiment a few times and each time it seemed to take 12 to 15 secs to empty the bucket. Lets use the slowest time and do the math.

5 gallons/15sec = 20gallon/min = 1200 GPH

I suspect that my less than scientific experiment introduced some lag in the actual emptying but for my purposes, 1200 GPH is within my target range.

Attaching some pics of the quick and dirty setup for those interested.
http://s1197.photobucket.com/user/biggertef/library/

I actually didn't use the second standpipe for anything yet. Maybe if I hook this thing up to an actual pump, I might drill a 3rd hole and make a full on bean animal test fixture, although I'm guessing if I do any more testing, I might replace the bucket with a bigger container such as a rubbermaid bin.

I hope this is useful for someone, it definitely was for me.

 

[biggertef]

Correction: 1.5" bulkheads do not take 3.5" holes.. I must have been smoking something. Correct hole size for these appears to be ~2.3"?